I have some 1# and 8# containers of H4350 from different lots I plan on mixing to create one more consistent "lot" of powder. The idea a larger amount of powder will be uniform and consistent.

I know some people say NEVER mix powder but I feel if it is safe to load various lots it should be safe to mix various lots (of the same powder type) and treat it as a new lot. Is that wrong?

Anyways, I am more concerned that either breaking the factory seals on powder containers that are to be mixed and stored or even the actual act of mixing and pouring powders may degrade or alter them.

Does anyone have any concerns or tips about anything like that?

Also, since this thread is about powder, how long do you guys keep powder in your powder dispenser? Are you worried constantly transferring powder from container to dispenser and back could degrade it?

Something I do is put a towel over my Chargemaster hopper if I leave it filled for any length of time to protect the powder from light. I have no idea if that does anything though.

Tell us why you do or don't do stuff with your powder.

I keep powder in my measure all the time.

I never leave powder in my chargemaster or rcbs powder measure.
Mainly because it stains the hopper and you can't see through it. Keep filled while actually loading, empty when done for the day.

As for mixing, I typically have 8 lb jugs. Check load when opening a new jug.  Though dad and I have mixed several lots of imr 4895 to make one large lot before.  Then built the load(s).

For storage, all mine are in the garage and most in a pelican case.  Either way, I wrap the cap with several layers of electrical tape after sealing them.  For the past 35+ years this method has served me well, as it was what my dad taught me and still does.

Also, whether you do or don't keep powder in the dispenser, keep that jug / container next to it or behind it.  You don't want to forget what is in there.......

Yup
3 of my measures are clearly labeled w/ the powder, throw weight, and cartridge it's meant for.

Interesting idea with the Pelican case and electrical tape.

As for mixing powder I had 24 pounds in different sized containers of different lots and wanted my powder consistent for as long as possible. I poured it all into a plastic tote but first I wiped it out with an anti static dryer sheet. I didn't want the powder clinging and I really didn't want a spark.

I tried a few different ways of getting it back into empty 8lb jugs but eventually settled on scooping it with an empty 1lb jug cut in half.

Having all that powder mixed I am leary about loading it all up. If something changes (my biggest worry being the powder shooting hotter over time for some reason) I don't want to have it all loaded live ammo.

No issues with it etching or staining the hopper?

I can't say so. They all have the baffle at the bottom so, as long as they're not full, the powder really doesn't ride on the tube (too much).

Eta: took some powder out so you could see tube clearly.

I've had TAC turn into a clump of goo in my powder measure before.  Would always seal air tight.

I mix lots of the SAME POWDER together, to uniform it...... No reason that would be a problem.  

I do not leave powder in hoppers unless I am actively loading.  
(Taking it in/out won't hurt it)
I'm concerned about mis-loading one powder into another load by mistake.  
It will also stain the hopper.  

Quality Powder stored properly will last a VERY long time.  
I don't worry about it breaking down...........so I load away.  
I bought the powder to shoot, not admire on a shelf.  
I usually use the winter months to load up for the year, so I'll load a few thousand or more............  

Thanks for the replies. I like hearing how different people do different steps in the reloading process and why.

I was reloading for quite a while when I got a bunch of case head separations. Someone asked how much I was sizing the brass and I said a quarter turn  of the die down after it touched the shoulder, just like the instructions for the die said.

I bought a case shoulder comparator and it turns out the manufacturer reccomended 1/4 turn of the die pushed the shoulder back a LOT, way way more than you would ever need to. The 0.0015" bump back I was looking  needed 1/32 of a turn to achieve.

I mentioned that because I was following a reloading guide from a reputable company but it was a terrible way to do things. When I would shoot with people we would talk about bullet BC, tripods, temperature, triggers, scopes, barrels, stocks, bags, range layout, rangefinders, powder types, powder charges, etc. and sizing never came up. It wasn't until I was at a match 600 miles from home and the problem came up and we started discussing it. And by discussing I mean me getting laughed at.

There are so many aspects of precision shooting and reloading that it's easy to overlook something. That's why I really like talking to other shooters and reloaders on forums like this.

And quick tip, if you get a case head separation with. 308/6.5ish sized case a copper or steel 5.56 chamber brush should have enough grab the pull out the case from the chamber. I always keep one in my pack now.

The problem with mixing even the same powder is that there are sometimes recals on powder.
Then what?
And powder high in nitro will destroy a plastic dispenser.

But Ive done it. Same powder into each other.
And I purchased glass hoppers.